19
YORK INTERNATIONAL
FORM 201.18-NM9 (602)
Thermal Overload
Three PTC (positive temperature coefficient) ther-
mistors in the motor windings of each phase provides
thermal protection. The sensor resistance stays relatively
constant at 1k
Ω
until a temperature of 266°F (130°C) is
sensed. The sensor experiences a rapid rise in resis-
tance beyond this temperature. Whenever the resistance
of one of the sensors reaches 13k
Ω
, the 2ACE module
trips, which ultimately de-energizes the motors pilot
circuit. Reset is manual after the motor cools and the
sensor resistance drops to 3.25k
Ω
.
Current Imbalance (Loaded & Unloaded)/
Loss of Phase
A 2 second delay at start-up allows for any imbalances
resulting during normal starting conditions. After this
initial delay, the 2ACE module compares the Operat-
ing Current to the measured half line current. The Op-
erating Current is given by 0.65 X factory overload
current setting.
2
An
unloaded compressor condition
occurs when any
measured half line current is less than the Operating
Current. A current imbalance exceeding an unloaded
level of 25% will result in the motor pilot circuit being
de-energized.
A
loaded compressor condition
occurs when any mea-
sured half line current is greater than or equal to the
Operating Current. A current imbalance exceeding a
loaded level of 17% will result in the motor pilot cir-
cuit being de-energized.
Imbalance
is defined as
(High Phase - Low Phase)/High Phase
Improper Phase Sequence
The 2ACE module calculates the phase sequence at
start-up using the three current transformers to deter-
mine whether the three phase sequence on the load side
of the main contactor is miswired. Upon detection of a
miswired motor load, the module will deenergize the
main contactor pilot circuit within 50 millisecond re-
sponse time.
Summary of Contents for eco YCAS Series
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